This invention relates to the projection television receiver art. Specifically, apparatus is provided for projecting a TV image derived from three kinescopes to an exterior screen.
Projection television receivers are old in the art. It has been known that color projection television receivers may be manufactured by using three separate kinescopes. Each kinescope is used to project an image comprised of one of the primary colors to a set of crossed dichroic mirrors. The kinescope images are transmitted through the dichroic mirrors and combined at a common point. The image thus located may be magnified and transmitted to a distant screen by use of a lens.
In the past, the lens used for transmitting and magnifying the recombined image has been color corrected. The color correction is required because light of different wave lengths will be magnified to different degrees since the focus of a lens is different for different wave lengths of light. The color correction techniques employed in many lenses are expensive and do not always provide the degree of compensation necessary. The excessive cost of color correcting a lens for projecting the television image reduces the commercial market for projection TV receivers.
Therefore, a projection TV system which would not require a color corrected lens for projecting a resulting image produced by the dichroic mirrors would be desirable.